A major manhunt is under way to find the fugitives
Mexican authorities have detained a prison governor and some 40 guards after an armed gang managed to free 53 inmates from a jail in central Mexico.
The attackers, some dressed as police officers, gained entry to the prison in Zacatecas state and freed the prisoners without firing a shot.
Zacatecas Governor Amalia Garcia Medina said security camera footage suggested the gang had had inside help.
Many of those on the run are believed to be drug gang hitmen.
A huge manhunt involving the army and federal police is under way across several states.
The jailbreak happened early on Saturday when a convoy of at least 15 vehicles arrived at the prison in Zacatecas.
The men announced that they were there for a prisoner transfer, officials said.
Once inside, they freed 53 inmates, many of them believed to be hitmen for a powerful drug-smuggling gang known as the Gulf Cartel.
Officials said 11 of the escapees were "very dangerous".
The prison governor, 40 guards and two police commanders who were on duty at the time have been taken into custody for questioning.
"It is clear to us that it was a perfectly planned operation with inside help because it lasted just five minutes and not one shot was fired," Gov Garcia told reporters.
President Felipe Calderon has declared war on drug-traffickers, deploying 40,000 troops to fight the cartels.
Some 10,000 people have died in the past two-and-a-half years, as the gangs fight for territory amid the government crackdown.
Progress in the war against the cartels has been limited by the fact that in the face of well-armed and well-financed drug cartels, this country's law and order institutions have proved weak and easily corruptible, the BBC's Stephen Gibbs in Mexico City says.